1. Field of the Invention
The present invention relates to an antenna device and an antenna system utilizing said antenna device, and particularly relates to a wideband antenna that can be hidden in a system and a wideband antenna system utilizing said wideband antenna device.
2. Description of the Prior Art
A popular type of a access-point antenna applied to a wireless wideband router/hub is a dipole antenna with a plastic or rubber sleeve encircling it. The dipole antenna is always located at one side of an apparatus, and the antenna is exposed on the case of a product. Such an antenna is prone to be vandalized, occupies a lot of space and affects the aesthetics, and it is even worse for a multi-antenna system where there are more than two antennas. FIG. 1 is a schematic diagram illustrating a prior art wideband router 100. As shown in FIG. 1, the wideband router 100 includes antennas 101, 103 and 105, but the antennas 101, 103 and 105 are exposed and have considerable sizes such that the antennas can easily be damaged by external force.
In order to solve these problems, some access-point antennas have been developed to be smaller and at the same time capable of providing wide bandwidth (2.4˜5.8 GHz). For example, a Taiwan patent with patent number M253071 discloses a “dual-band antenna”, which utilizes a dual-band access-point dipole antenna structure. The antenna utilizes two radiating copper tubes to reach the 2.4 and 5 GHz dual-band operation, and this operation is different from a prior art single band dipole antenna that utilizes a center conducting line of the coaxial cable. Additionally, a Taiwan patent I227953 discloses a “broadband dipole antenna”, which discloses a broadband access-point dipole antenna structure. The antenna includes two metal sleeves and a radiating metal line. By controlling the relative positions of both metal sleeves and the radiating metal line, good impedance matching in the 2.4-5.8 GHz band can be obtained, leading to a wideband operation. However, for the above-mentioned antennas, there is still a need for an extra plastic/rubber sleeve to wrap around the antenna, which causes an increase in the complexity and antenna cost. Furthermore, such antennas cannot be hidden inside a wireless wideband router/hub; that is, the antenna must be external, and therefore the aesthetics of the product decreases.
Therefore, a new invention is needed to solve the related problems.